1. Field of Invention
Embodiments of the present invention relate to an electronic musical instrument. In particular, embodiments of the invention relate to an electronic musical instrument in which a phrase is played back at a tempo that has been set by a user, and in which the user may temporarily change the tempo at which the phrase is played back using a readout position change operator.
2. Related Technology
Electronic musical instruments that play back waveform data representing a phrase comprised of a plurality of bars of musical tones have been known for some time. Some electronic musical instruments allow the playback tempo of the waveform data to be changed. In such instruments, the original tempo of the waveform data is compared to the tempo at which playback is to be carried out, and a difference is determined. Playback of the waveform data is then performed based on the difference. However, it is not possible to change the playback tempo of the waveform data once playback has begun. In this regard, the applicant has proposed in Japanese Unexamined Patent Application Publication (Kokai) Number 2001-188544 an electronic musical instrument that allows a tempo change to occur during playback of waveform data. In this system, a tempo difference is determined at specified periods during playback and playback is carried out while successively modifying the playback position for the waveform data in conformance with the tempo difference at each period.
Other known electronic musical instruments allow the readout position of waveform data to be controlled by the user through the use of an operator. However, in such instruments, the user directly controls the readout position of the waveform data without reference to the amount of the adjustment in units of musical time, making it difficult to adjust playback to a desired position. In this regard, the applicant has proposed in U.S. Published Patent Application Number 2002-0046639 an electronic musical instrument in which the user is enabled to adjust the readout position of waveform data in units of musical time. This enables the performer to adjust the readout position in a manner that produces a predictable performance.
However, in the aforementioned electronic musical instruments, if the readout position of the waveform data is changed during playback at a tempo that has been previously synchronized to another performance such as an accompaniment, the resulting change in readout prevents playback from returning to synchronization with the accompaniment when the readout position change is canceled.